This invention relates to solenoid coils for energizing the starting motor for internal combustion engines, and more particularly, to a switching arrangement therefor which will solve the problem of switch erosion caused by arcing across the switch contacts.
A number of prior patents including U.S. Pat. No. 3,543,047; No. 3,736,466; and No. 3,982,137 have addressed the problem of arcing across switch contacts. These patents have all utilized some type of electronic component, such as a varistor or thyristor which is utilized to increase the impedance across a set of switch contacts to reduce current flow and consequent arcing thereacross when the contacts are opened.
Another U.S. Pat. No. 4,801,909, relating to a solenoid for a starter motor, deals with the problem of solenoid contacts sticking "closed." In this patent, a tiltable contact arm is adapted to provide equipotential at one set of contacts whereby any sticking will necessarily occur at the other set of contacts. A seesaw or lever type action results in a "torque" being exerted to force the stuck contact arm free of its engagement with the fixed terminal. While this patent relates to the problem of sticking switch contacts, it does not solve the underlying problem of reducing arcing caused when a current-carrying mechanical switch is opened.
The principal object of this invention is to provide a solenoid switch for energizing a starter motor for an internal combustion engine which has a simple but effective mechanical switch arrangement for minimizing the problem of electrical arcing across the switch contacts which are adapted to "open" when the solenoid is de-energized.
Another object of this invention is to provide an integral solenoid for energizing a starter motor having at least four poles in which the switches for the motor coils are connected in parallel and in which the switch to the electrical energy source is disposed to close, or "make", before and break after the switches to the motor coils so that upon opening of the switches, electrical arcing across each switch is minimized.
A further object of this invention is to provide a solenoid of the above type in which the solenoid and motor are of compact overall size.
Yet another object of this invention is to provide a solenoid of the above type with a switch construction which utilizes a single axially movable and tiltable contact adapted to engage, in sequence, upon axial movement thereof, a fixed high potential contact and thereafter, upon tilting movement thereof, it engages other switch contacts connected to energize the starter motor and to de-energize the starter motor in reverse sequence .